Regarding how mankind can prepare themselves. Small cooperative groups, operating in Service-to- Others, where the concerns of all are the concerns of each, will have the best chances. Most important is a cooperative attitude among the group, with a willingness to undertake distasteful tasks, a desire to share among all what little there may be, and a positive attitude toward the future.
Sunlight may be Scarce, so crops grown under artificial light will be most abundant. Rivers and seas may be poisoned, what with the volcanic dust falling everywhere, so fish tanks fed from algae grown in human sewage will likewise be most abundant. Certain crops fair better and go further than others. Good cooks, skilled at making the plain fare tasty, will be much appreciated. A natural way of life reminiscent of life during the last century.
It is no small matter to have music, poetry, and art. This fills the heart of the musician, poet, or artist as much as the recipient. There will be much need for such distraction, as the days will be dim, and the nights dark and long. But do plan to educate your young. Save Educational Material. There is no reason that technology should stop, just because the infrastructure of human society has been torn asunder. Technology is in the minds and documentation that all humans can access, and rescue.